Penalty area is a body of water or an other area defined by the Committee where a ball is often lost or unable to be played. It could be a lake, pond, river or the sea, but also a dry drainage ditch as well as just forest, thickets, desert, rock fields and other areas without any water.
Penalty areas are defined as either red or yellow. The color affects relief options available to players (for one penalty stroke) if their balls come to rest in this area. If the color has not been marked or indicated the area is treated as a red penalty area.
Individual Committees are free to choose what to mark as a penalty area. They could decide to mark only traditional water hazards.
They can also choose when to mark a penalty area as yellow. So that they can mark all penalty areas as red at their discretion, always allowing for lateral relief.
Yellow penalty area
Red penalty area
When a ball is in PA?
The edges of penalty areas are usually marked with painted lines and/or stakes of the appropriate color (yellow or red).
When the edge of penalty area defined by a painted line on the ground, it is defined by the outside edge of the line. In such case the stakes show only where the penalty area is, but they have no other meaning.
See the picture below – the boundary edge of the penalty area is marked by black dashed line.
update: March 2021